Loughborough University
PE Energy Paper_EGY-S-19-03429R2_no change marked.pdf (1.28 MB)

An experimental investigation of the heat transfer and energy storage characteristics of a compact latent heat thermal energy storage system for domestic hot water applications

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journal contribution
posted on 2019-09-11, 11:12 authored by Mohamed Fadl, Philip EamesPhilip Eames
This paper presents the experimental performance analysis of a latent heat thermal energy storage system (LHTESS) designed for domestic hot water (DHW) applications. The designed, fabricated and characterised thermal store comprised of a vertically oriented multi-pass tube heat exchanger in a rectangular cross-section container filled with phase change material (PCM) paraffin wax RT44HC. The experimental investigation evaluated the heat transfer within the system, measured the transient temperature distribution, determined the cumulative thermal energy stored, charging and discharging time and the instantaneous charging and discharging power. The experimental work was conducted under controlled experimental conditions using different heat transfer fluid (HTF) inlet temperatures and different volume flow rates for store charging and discharging. It was found that during charging natural convection in the melt played a significant role. During discharging thermal conduction dominates and natural convection has an insignificant impact on the LHTESS performance. This is due to the development of a solid layer of PCM around the heat transfer tubes which increases the thermal resistance and reduces heat transfer to the liquid PCM. Higher HTF inlet temperature during charging significantly decreased store charging time. Increasing HTF inlet temperature from 60 to 70 °C shortened the charging time by 3.5 h, a further increase to 80 °C decreased melting time by a further 2 h.

This study illustrates the extent to which LHTESS, and heat exchanger designs need to be improved to meet the desired charge/discharge time requirements for most short-term storage applications and that a broad range of domestic and commercial heat demands can be fulfilled by assembling several LHTESS units to operate in parallel.


Engineering and Physical Sciences Research Council (EPSRC) Grant reference EP/N021304/1(Small Smart Sustainable Systems for future Domestic Hot Water (4S-DHW) and EP/K011847/1 Interdisciplinary Centre for Storage, Transformation and Upgrading of Thermal Energy (i-STUTE)



  • Mechanical, Electrical and Manufacturing Engineering

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Elsevier BV


  • AM (Accepted Manuscript)

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© Elsevier Ltd.

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This paper was accepted for publication in the journal Energy and the definitive published version is available at https://doi.org/10.1016/j.energy.2019.116083.

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  • en


Dr Mohamed Sakr Fadl

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